坪田浅埋偏压隧道二次衬砌开裂机理及处治措施

Mechanism and Treatment Measures of Secondary Lining Crack of Pingtian Shallow Buried Bias Tunnel

以武(汉)深(圳)高速公路坪田浅埋偏压隧道为研究对象,首先基于隧道二次衬砌开裂情况分析了二次衬砌开裂的影响因素,然后通过有限元分析软件MIDAS GTS NX模拟双侧壁导坑法施工过程,分析了二次衬砌开裂机理。结果表明:二次衬砌最大拉应力区主要集中在拱顶偏左拱腰和仰拱处,其值接近或超过二次衬砌混凝土抗拉强度设计值;裂缝基本分布在侧向偏压作用线两侧。结合监测数据和二次衬砌实际开裂情况,最终对隧道采取了"洞内临时支撑+底板注浆+洞外坡体注浆"的综合处治方案。

Taking the Pingtian shallow buried bias tunnel of Wuhan to Shenzhen expressway as the research object,the inf luencing factors of secondary lining crack were analyzed based on the crack situation of tunnel secondary lining,the construction process of double side drift method was simulated by f inite element analysis software MIDAS GTS NX,and the crack mechanism of secondary lining was analyzed.The results show that the maximum tensile stress zone of the secondary lining mainly concentrates on the left arch waist of the vault and the inverted arch,which value is close to or more than the tensile strength design value of the secondary lining concrete,and the cracks are basically distributed on both sides of the lateral bias action line.Combining the monitoring data and the actual crack of the secondary lining,the comprehensive treatment scheme of“temporary support in the cave+f loor grouting+grouting outside the cave”was adopted for tunnel.